I use two batteries currently. I generally give it 5 mins to cool down before I go again, although saying that, I should imagine that the prop wash would provide adequate cooling for the motors. Grab them and see how hot they are when you power off; that will give you a decent indication.

 

If the motors don't burn your fingers, then you're fine. They self cool as you fly.

 

Here in Florida the Sun is intense this time of year and I usually fly in the afternoon when the sun is beaming.

I have 5 batteries and 3 is the most I would fly back to back without cooldown. With full sun after the second battery the top of the H can get quite warm, although I usually give the H at least 5-10 mins between flights.

 

My H just came back from Yuneec customer service and one of several issues that I reported to them was the top of the H body gets very hot, the answer I got from their service manager was the gps unit does run hot and is quite normal.

 

The motor temp during touch method works good for determining what the motors may need. Unless flying with the GPS turned off it's doubtful they would become too hot. Flying high speed and pulling a lot more amps with GPS off might well generate more heat at the motors and ECSs, requiring some cool down time. Tossing a white towel over the top of the H when sitting in the sun while not being used might not be a bad idea to help keep inside temps down a little bit. We've been doing that with RC airplanes for years to keep the electronics cooler. Lifting it away from the hot ground where it collects a lot of reflected heat is also not a bad idea. If it's 100* in the air the ground is probably 20*+ more than that if it's bare dirt, concrete, or asphalt.

I just did a 3 day shoot that kept batteries changing out back to back in 95* heat with no problems at the H side of things but just after completion the ST-16 started complaining and required re-calibrating all the controls along with the button and switch functions. I don't know that was from getting used heavily in the hot sun, sitting too long in a hot car, or just one of those things. Interestingly, communication of the problem was provided by the H, not the controller.

 

I check my motors after each battery to see if they are hot. If they are hot or very warm I'll let them cool down. Its also a good way to determine if you have a motor problem developing. If one or two motors are hot and the others are not, it maybe something you need to keep an eye on...

Even in warm weather here with temps in the low 90s, the motors have not been hot, just mildly warm...

 

For me, the motors get warm, but not too hot to touch. But the electronics inside the drone measured with an IR laser temp gun can get up to 150° (measured through the battery opening). This is in 90-95° temps in california. So I'm guessing that yours is getting hotter in the over 100° weather. To me, this is too hot for the electronics. Not sure what the specs are, but if it's hot enough to burn your finger, then it's too hot (not that I did that). Batteries usually measure 112-116° after flight, but can get up to 120° in high heat (95°). I usually let it cool down for about 10 mins between flights.

 

Heat and cold are not your friend. You need to keep an eye on it. 150* inside is enough to start melting the circuits. These ac are just like computers, the rules that govern them will also govern TH.

 

A very large percentage of electrical components are temp rated to 60C, and those rated are just the ones that have been tested in order to qualify for use in products where design certification standards are employed. Our toys do not have to meet any design or certification standards, we get whatever is cheapest. That status is pretty much across the board with hobby grade products from every maker.

 

While flying the body and motors should cool by convection. Sitting still with no wind to move through the body to move the air out may pose a problem, but since nobody has actually measured temps inside the body it's anyone's guess. One would have to assume (hope ?) Yuneec did sufficient testing. When landing this cooling stops so all the heat is trapped inside the shell and feels hotter than it is while moving. Personally I don't like how how hot the battery is when removing it on hot days, but may be perfectly fine.

I've never liked hot running motors. There is no maintenance recommendation for the H motors such as do the bearings need to be oiled, MTBF and all that. I have an extra motor and will disassemble it to see if it can be determined who actually makes them which should have all the specs.

The motors on my two larger quads (DIY) stay cool no matter the air temp as they are much larger and well within design intent. Also, since all the electronics (FC, ESC et al) are exposed to the air, heat has never been something I worried about. The exception is the Sky Hero 750 Y6 which has the ESC's inside the arms which I've never cared for.

So the question is, what exactly is "hot"?

 

60°C is only 140°F, so we're running really hot
There doesn't seem to be much airflow going through the body. I'm not sure if the battery is heating up the electronics/esc's or the other way around or both, but it's definitely getting hot!

 

Me? After landing I have a smoke of a cigarette before shoving another battery in. Works for me (but not too great on my lungs lol)

 

During "normal" flying the battery is not heating up. Full throttle in Angle mode doesn't pull all that many amps. Full throttle GPS off likely pulls a whole lot of amps, which would explain the rapid drop in battery voltage. There's the possibility all that extra speed is obtained by nearing the max C rating of the battery.

The electronics are stacked, which tends to generate quite a bit of heat but we need to remember the H is black, a color that absorbs BTU's. They make solar panels black for a reason. If anyone doubts that black is a BTU collector, just put your hand on the top of a white car and a black car in a parking lot on a 100* day. You'll instantly note the difference. If ventilation is lacking the interior will act like a convection oven, absorbing and retaining heat while experiencing additional heat generation from the electronics. Good cooling air flow becomes pretty important under those conditions.

 

Do you think another well known manufacturer chose white for their craft as they foresaw that the sun's heat could be a problem - or is white plastic cheaper?
We could just put some white gaffer tape on the top area of our H if need be.

 

I think it simply has to do with a neutral color that is generally acceptable to the vast majority of the public. Some companies spend a ton of money on color selection for their product to best appeal to the buying public. Some colors turn people away from a product.

White or Black are usually safe bets...